1. Field of Invention
This invention relates to insulation panels used for building construction, and particularly to insulation panels used for roofing construction.
2. Prior Art and Other Considerations
An effective prefabricated thermal insulation panel is inherently self-destructing. That is, in insulating a building for the purpose of conserving energy, the panel stores high levels of heat. Such intense heat is deleterious to the panel structure per se. This heat build-up problem is especially acute in the roofing environment. The heat build-up problem is especially severe when the insulation panel comprises a sheet of high efficiency plastic foam.
The prior art includes panels wherein air circulation is provided to keep the panels as cool as possible. Examples of such prior art panels include those illustrated in U.S. Pat. No. 4,852,314 to Moore, Jr.; U.S. Pat. No. 4,635,419 to Forrest; U.S. Pat. No. 4,254,598 to Rugroden; U.S. Pat. No. 3,756,895 to Bellamy; and, U.S. Pat. No. 1,028,725 to Hodgson.
The prior art insulation panels such as those listed above generally comprise two flat sheets which are oriented parallel to one another and spaced apart by a plurality of spacer members sandwiched therebetween. The spacer members are positioned relative to one another to define air channels. The air channels are thus bordered above and below by the flat sheets and are laterally bounded by the spacer members. The channels allow air to pass between the top deck and the insulation board, thus causing a cooling effect on all components.
In the effort to keep costs down, most manufacturers have used wooden 3/4 thick inch "furring strips" as the spacer members. These furring strips are less than three inches wide, and thus may require as many as five strips to be placed within a forty-eight inch length. When wood furring strips are used as the spacer members to create the air channels, the wood lowers the thermal resistance values (increases thermal conductance) of the insulative building panel within the area where wood furring strips are used. In Northern winters, these areas can be seen on a roof as strips of melted snow.
All building products manufacturers have experienced strong incentive to reduce manufacturing costs. The need to obtain improved performance and yet reduce costs persists.
It is therefore an object of the present invention to provide a vented, insulative building panel having even insulation distribution.
An advantage of the present invention is the provision of an insulative building panel the construction of which avoids using new and unused lumber as furring strips, thereby conserving one of the earth's precious natural resources.
A further advantage of the present invention is the provision of an insulative building panel which advantageously utilizes scrap, or waste, materials as spacer members, which materials would otherwise be discarded and further congest refuse disposal facilities such as landfills.
Another advantage of the present invention is the provision of an insulative building panel which reduces the number of spacer members required along any given dimension.
Still another advantage of the present invention is the provision of a lighter weight vented insulation panel having comparable load bearing strength.
Yet another advantage of the present invention is the ability to make insulative building panels according to the invention having an essentially unlimited range of cross sectional ventilating channel area, while maintaining compressive load and strength requirements.
Another advantage of the present invention is the provision of an insulation panel with better thermal resistance per equal thickness when compared to prior art panels.
Yet another advantage of the present invention is the provision of an insulation panel which requires less expense to manufacture, thus lowering the cost of building construction, particularly for sloped roofs.